Creo que no hay opción para elegir , simplemente te ingresaran la pasta y te borraran las acciones:
https://otp.investis.com/clients/us/monsanto/SEC/sec-show.aspx?FilingId=12801849&Cik=0001110783&Type=PDF&hasPdf=1
"...The merger between Monsanto Company and KWA Investment Co., an indirect wholly owned subsidiary of Bayer Aktiengesellschaft, became effective before market open on June 7, 2018. Each Monsanto Company Common Stock was converted into USD 128.00 in cash...."
Un Saludo: